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Re: [Phys-l] Transparency



On Oct 12, 2008, at 6:57 PM, Brian Whatcott wrote:
. . . This old paper in Phys Rev A 7 mentions an analogous effect,
the laser etched tracks in glasses and polymers.

<http://prola.aps.org/abstract/PRA/v7/i2/p734_1>http://prola.aps.org/abstract/PRA/v7/i2/p734_1

1) The second author is one of the three people who developed track detectors at GE (first based on mica and later on glasses and other materials).

2) But I have a difficulty with the first sentence: "Self-focused laser filament tracks in various glasses and polymers were chemically etched . . ." They probably wanted to say that "filament tracks, created by a laser beam, were etched . . . " It is the "self-focused" part that confuses me. It probably refers to a laser beam, not to its track. How can a beam be "self-focused" ? It can be focused by a mirror or a lens. What am I missing?

Ludwik Kowalski, a retired physics teacher
5 Horizon Road, Apt. 2702, Fort Lee, NJ, 07024, USA
Also an amateur journalist at http://csam.montclair.edu/~kowalski/cf/